MDL-40913 core_message: replaced 'add contact' add_to_log call with an event
MDL-40913 core_message: replaced 'remove contact' add_to_log call with an event
MDL-40913 core_message: replaced 'block contact' add_to_log call with an event
MDL-40913 core_message: replaced 'unblock contact' add_to_log call with an event
MDL-40913 core_message: replaced 'write' add_to_log call with an event
MDL-40913 core_message: created 'message_read' event
MDL-40913 core_message: removed 'view' add_to_log call